The present inventive concept relates to semiconductor memory devices and methods of operating same. More particularly, the inventive concept relates to semiconductor memory devices that are capable of correcting errors in fuse data and methods of operating same.
Contemporary semiconductor memory devices often include redundancy memory cell arrays that are used to replace defective memory cells in a primary (or main) memory cell array. The replacement of defective memory cells with redundant memory cells allows more efficient and reliable use of the memory cell array during read and write (programming) operations. The redundant memory cells may be used as replacements on a sub-array block basis, a row-by-row basis, a column-by-column basis, or an individual memory cell-by-memory cell basis.
Following fabrication of the memory cell array at some point during the wafer stage of manufacturing, defective memory cells are identified by standard tests, and information regarding the defective memory cells is stored. Defective memory cell information is often stored in a nonvolatile manner using one or more array(s) of fuses. Individual fuses may be variously and selectively programmed or not-programmed by (e.g.) application of electrical current or a laser beam to particular portion(s) of the fuse.
An anti-fuse element is a well-known element that includes one electrode (a first terminal), an intervening insulating material, and an opposing electrode (a second terminal). A voltage difference between terminals of the anti-fuse element may be used to destroy the insulating material causing the two electrodes to short-circuit. A voltage that destroys the insulating material of the anti-fuse element is referred to as a programming voltage. Using this programming voltage, fuse data (e.g., information regarding defective memory cells) may be stored in the anti-fuse element.
However, during operation of the semiconductor memory device, some anti-fuse elements may malfunction. Such malfunctions are a cause for concern since anti-fuses may not be fixed during normal operations of the semiconductor memory device.